Hi Guys, Recently joined the forum, not new to getting my hands dirty though So we're in the process of doing up the kitchen, and the extension that we had built some 20-25 years ago has a pitched roof, was a bedroom with standard flat ceiling beneath. We have removed this ceiling, relocated the bedroom and are installing a 1600x900 landscaped format rooflight that weighs approx 140kg. The rafters used are 5x2, I will install 75mm celotex insulation between and 50mm celotex to the underside, allowing a 50mm gap between insulation and where the underlay is. Anyway, since I have some scope due to the insulation build up I thought I'd use 6x2 C24 doubled up bolted every 400mm to support the rooflight rather than tripling up the 5x2's. Where the 6x2 intersect I will use some 25mm rigid insulation, as the 50mm will not be able to go over this. The length of the rafter is just under 3100mm. I think the above would be adequte to support the rooflight, but would be interested to hear any thoughts. Hope the above makes sense. Thanks for reading. Mo.